Refrigerating apparatus



in-s1 July 12, 1960 Filed Oct. 6, 1955 L. .1. MANN ETAL 2,944,410

REFRIGERATING APPARATUS 3 Sheets-Sheet 1 z J'WW 60/76! a? a; 2222/? lukjykirm ii THEIR ATTORNE) July 12, 1960 L. J. MANN ETAL 2,944,410

REFRIGERATING APPARATUS Filed om. e, 1955 3 Sheets-Sheet 2 ggy ZINVENTORS HE/l? lqrromvsv July 12, 1960 L. J. MANN ETAL REFRIGERATINGAPPARATUS Filed 001.- .6, 1955 3 Sheets-Sheet 5 THE/R, A'rromvsr Unitedsass 2 44,410 REFRIGERATJNG APPARATUS Leonard J. Mann, John Murphy, andClifford H.

Wurt z, Dayton, Ohio, assignors to General Motors Corporation, Detroit,Mi a corporation of Dela.- ware a v Fi O 6, v N9- 538 92 3 Claims. 7 c1.62-;86)

lems in view ofthejfact that the refrigeration oa each compartmentfluctuates unevenly. r

It is an object of this invention to providea simple and inexpensivecontrol which" makes it"possi'hle to maintain the temperature in eachofthe compartments; sub- 'stanti'ally constant'at all times irrespectiveof: theffluctuations in refrigeration requirements in the different foodcompartments. I l

More particularly, it is anpbject of this invention to provide arefrigerating system in which a fan circulates air over the second oftwo series connected evaporators and in which the refrigerant liquefyingapparatus is cycled by a thermostat located in" contact with this,second evap; orator and; the fan isseparately cycled in response tochanges in the rem erame of the air'leaving second evaporator. V a t Itis another object of this invention to provide anirn;

proved type of automaticdefrosting arrangement in a refrigerator of thetype using forced air circu ation over a portion of theevaporator.

Further objects and advantages ofthe present invention will be apparentfrom the;followingdescriptionr ifi rence being had to the cc mpany n rwin s. preferred form of the present) invention is; clearly shown. Inthedrawings:

Figure l is a perspective view showing a preferred embodiment of theinvention; I

Figure 2 is a vertical sectional view showing the arrangement of theevaporatorsrelative to the food storage compartmentsand Figure 3 is afragmentary sectional view taken substantially on line 3-3 of Fig. 2,showing the one evapo-. rator in the air fine and schematicallyshowingtheirefrigerant circuit.

Referring now to .the drawing, wherein av preferred em.- bodiment of theinventionhas been. shown,..reference numeral 10 generally designates a.household refrigerator having a motor-compressor compartment12,.a.fr'ozen food storage compartment 14, amainfood storage com-.partment 16 for storingunfrozen foods. anduashydrator 1'8 pivotallysupported onjthe mainrefrigerator door20. The refrigerator comprises.the. usual sheetv metal outer shell 22. which servesto.supportapair,ofinner liner ele ments, and 26- which form the frozen:food. compartment and the unfrozen, foodstorage compartment, respec-.tiyely. Suitable insulation: 28 iswprovided: betweenwtheouter shell 22and theinner liners inzaccordan'cewith standard practice. v I V V 7 Themain door-20 isprovidedwith one or more shelves wherein a,

;1iitent d my a l-asa 2 V I 3.0 foruse in storing such articles as eggsand condiments and also serves as a support for the hydrator 18.

For a more detailed description of the construction of the hydrator,reference is hereby made to our copending application, Ser. No. 418,668,filed March 25, 1954, now Patent Number 2,859,595, which shows anearlier version of the refrigerator disclosed herein. 3

The refrigerating system which is used for cooling the food stored inthe compartments 14, 16 and 18 consists of the usual motor-compressorunit 50 which is preferably of the hermetically sealed rotary type whichis now very well known and needs no further description. The compressedrefrigerant leaving the. compressor 50 flows into the condenser 52 fromwhence the liquid refrigerant flows through -a conventional fixedrestrictor type Of'PFCSSUIG reducing device 54. Insofar ascertainaspects ofthis invention are concerned .any type of pressure:reducing means may be used such as an automatic expansion valve or athermostatic expansion valve.

-In the preferred embodiment of the invention, a fixed restrictor isused and servesto convey liquid refrigerant into a first primaryevaporator 56 which is incorporated inthe liner 24 of the, frozen foodcompartment 14 After the, evaporatorv5 6 has been filled, with. liquidrefrigerant the surplus refrigerant flows through an unrestrictedpassage, 58 into. a second primary evaporator tiliwhich. is

mounted in an air 1111610 at the; back of the compartment 1'6 and servesto cool the main food storage compartment 16 in a manner to beeXplainedrnorefully hereinafter;

The second evaporatorotlconsists of a rollbonded; plate which has beenmanufactured by the process disclosedin US. Patent Nos. 2,662,273 and2,712,736. The liquid refrigerant leavingthe first evaporator 56 enterstheevaporator 60.. through the line 58 which leadsto a wafiie+ platetype of' accumulator and primary evaporator passage 61-. The refrigerantleavingthe passage 61 flowsthrough 'apassage-63into thebottom-ofiasecond wafiie=plate type ofaccuinulator .and refrigemntpassage 65 which' is arranged, as shown. The outlet-from-the'passage 65:is connected to a plate: typeaccumulator 67 located in the return line62 v which leads to the inlet of the motorcompressor. unit 50.;Thewaiflerpla-te -type of accumulator passages 61 and. 65 serve thedual: purpose of storing sur plusrefrigerantand as disengagingpassageswhich pre vent the. vaporized refrigerant from sweeping slugs of liquid.refrigerant into the suction line 62.-

Invi'ew of the fact that the capacity of the primaryevaporators 56 and60,- will varyfrom one refrigerator to another due to the inabilityor-impracticabilityofmanu factoring; all evaporators exactly alike; somemeans. must be provided for compensating for such variations:F'urtlierrnore; changes: in ambient temperatures andchangesinrefrigerant loads will'cause rather-wide variaa tionsin thequantity; of liquid refrigerantin;the-evapo rators 56 and60-with-theresult-that in at'lea'stzsome' of: the. refrigerators therewill be a tendency-'at timesfor liquidrefrigerant to enter thersuctionline 621 BYrVlI'tllQ of the platetype accumulator 67 being arranged: indi-rect thermal exchange relationship;- with v theend: walhof the frozenfood compartment liner- 24: this surplus liquid refrigerant will bevaporized in-the)- aceumul'ator67 so as: to: usefully refrigerate thefrozen; food-compartment 1'4? At-snchtimes; when no liquidf refrigerantspills over into the suction line 62 the plate type accumulator 67*fserve 'toremove super heats-from the relatively warm refrigerahhvaporleaving the 'plate' ty'pe evaporator 60.

The "evaporator; 60' ismounted in the air fine 711% ar-f an outlet 74adjacent the upper portion of the compartment 16. A fan 76 is used forforcefully circulating air through the flue so as to cool the air andthen discharge it forwardly adjacent the upper portion of the compartement 16. The air then flows downwardly in thermal exchange relationshipwith the food stored on the door shelves and part of the air flowsbetween the hydrator 18 and the door and some of the air short-circuitsdown through the main portion of the food storage compartment on its wayto the return air inlet 72. By virtue of this forced air circulationarrangement and by virtue of the fact that the food shelves and hydratorare constructed so as to facilitate the circulation of air, it isobvious that no pockets of stagnant air will form during normaloperation of the apparatus. The fan 76 is offset from the bottom of theevaporator 60 as as to be out of the path of defrost water draining fromthe evaporator 60, as best shown in Fig. 3. The lower end of the flueand the blower extend into the compartment 16, as best shown in Fig. 2,so as to allow space for insulation'between the rear of the blowerassembly and the outer shell 22.

The control for the motor-compressor unit consists of a thermostaticbulb 80 mounted on the upper end of the evaporator 60, as shown.This'bulb operates a switch 82 (Fig. 3) arranged in the circuit 83leading to the motor-compressor unit 50 so as to start and stop theunit50 in accordance with temperatures of the evaporator' 60. The switch82 is preferably set to stop the operation of the motor-compressor unitwhen the temperature of the plate '60 drops down to -15 F. and restartsthe compressor when the temperature at the bulb 80 reaches a value ofsomewhere between 34 and 36 F. By virtue of this type of control and therefrigerant circuit arrangement shown, together with the proportions ofthe evaporators to the size of the compartment to be cooled, it ispossible to maintain the desired temperature differential between thefrozen food compartment 14 and the unfrozen food compartment 16 at alltimes and to cause the evaporator 60 to defrost itself during each Offcycle without melting any of the frozen foods. The switch 82 includesthe usual cold control adjustment 84 which enables one to adjust the,setting of the switch 82 so as to maintain either colder or warmertemperatures in the frozen food compartment 14.

The fan 76 is adapted to be cycled by means of a thermostat 85 locatedin the path of the air leaving the upper end of the flue 70. Thisthermostat is shielded by a plastic plate 87 which prevents the outgoingair from directly contacting the thermostat 85. This plastic plate 87serves to retard the response of the thermostat 85 in a manner toprevent short-cycling of the fan 76. The thermostat 85 controls a switch89 which is arranged in the circuit 91 of the fan 76. The switch 89 ispreferably set to close the circuit to the fan 76 whenever thetemperature at the thermostat bulb 85 is above 30 and is adapted tomaintain the circuit closed until the temperature at the bulb 85 dropsto a value of approximately 23 at which time the circuit to the fan 76is opened. It has been found that the construction and arrangementdescribed hereinabove makes it possible to maintain the air temperaturein the compartment 16 at a very constant value of approximately 36irrespective of changes in the outside air temperature and changes inrefrigeration requirements resulting from frequent opening of the door20 or resulting from variations in the amount and temperature of thefood placed in the refrigerator.

The frozen food compartment 14 is provided with an inner door 90 whichprevents the free circulation of air between the compartments 14 and 16and which prevents air from entering the frozen food compartment 14 eachtime the door 20 is opened. The compartment 14 is provided with theusual ice-tray shelves 92 which serve to support ice trays 94. Theevaporator 56 is large enough in proportion to the size ofthe'compartment 14 so as to maintain the temperature in the compartment14 at or near 0 F. depending upon the setting of the cold control 84,with the result that water may be frozen in the trays as needed.

Since the evaporator '56 is the first to receive any liquid refrigerant,it is obvious that the frozen food com partment will be maintainedproperly refrigerated at all times before any of the surplus refrigerantwill flow upwardly into the second evaporator 60. It is also obviousthat when the compressor stops operating, the refrigerant in theevaporator can drain down into the first evaporator portion 56 so as tocontinue refrigerating the frozen food compartment after the last of therefrigerant has been vaporized in the evaporator 60.

During the Off cycle of the motor-compressor unit 50, when the last ofthe refrigerant in the evaporator 60 has been vaporized, the air flowingover the evaporator will quickly raise the temperature of the evaporatorabove the freezing point of the frost on the evaporator so as to therebycause defrosting of the same. The defrost water drains from the bottomof the flue 70 through a slot 95 into the bottom portion of the foodcompartment 16 from whence it enters a drain 100 which conveys thecondensate water down into a pan 102 arranged in thermal exchangerelationship with the relatively hot condenser 52 so as to causeevaporization of the defrost water. The drain 100 includes a drain tube104 which by-passes the freezer compartment 14 and the insulationsurrounding the compartment 14.

While the form of embodiment of the invention as hereindisclosedconstitutes a preferred form, it is to be understood that other formsmight be adopted, as may come within the scope of the claims whichfollow.

What is claimed is as follows:

1. In a refrigerator, a cabinet having a first compartment for storageof frozen foods and a second compartment for the storage of unfrozenfoods, a first evaporator arranged in thermal exchange relationship withsaid first compartment, a second evaporator for cooling air for saidsecond compartment, refrigerant liquefying means, refrigerantfiow meansfor supplying liquid refrigerant from said refrigerant liquefying meansto said first and second evaporators in series, said refrigerant flowmeans including pressure reducing means adjacent the inlet of said firstevaporator, said second evaporator being connected to the outlet of saidfirst evaporator so as to receive the overflow refrigerant from saidfirst evaporator, means responsive to the temperature of one portion ofsaid second evaporator for controlling the operation of said refrigerantliquefying means, fan means forcefully circulating air from said secondcompartment into thermal exchange relationship with said secondevaporator, means responsive to the temperature of the air leaving saidsecond evaporator for starting and stopping the operation of said fan,said last named means including a temperature sensing bulb and means forshielding said bulb from direct contact with the air discharged by saidfan means.

2. In a refrigerator, a cabinet having a first compartment for storageof frozen foods and a second compartment for the storage of unfrozenfoods, a first evaporator arranged in thermal exchange relationship withsaid first compartment, a second evaporator for cooling said secondcompartment, a compressor, a condenser, refrigerant flow meansconnecting said evaporators, compressor, and condenser in series flowrelationship, pressure reducing means in said refrigerant flow'meansbetween said condenser and said first evaporator, said second evaporatorbeing directly connected to the outlet of said first evaporator was toreceive the overflow refrigerant from said first evaporator, meansforming an air flue adjacent one wall of said second compartment, saidsecond evaporator being mounted in said air flue, fan means forcefullycirculating air from said second compartment throughrsaid air. flue inthermal exchange relationship with said second evaporator, and meansresponsive to the temperature of the air at the outlet of said air fluefor starting and stopping said fan means.

3. In a refrigerator, a cabinet having a first compartment for storageof frozen foods and a second compartment for the storage of unfrozenfoods, a first evaporator arranged in thermal exchange relationship withsaid first compartment, a compressor, a condenser, refrigerant flowmeans connecting said evaporators, compressor, and condenser in seriesflow relationship, pressure reducing means in said refrigerant flowmeans between said condenser and said first evaporator, said secondevaporator being directly connected to the outlet of said firstevaporator so as to receive the overflow refrigerant from said firstevaporator, means forming an air flue adjacent one Wall of said secondcompartment, said second evaporator being mounted in said air flue, fanmeans forcefully circulating air from said second compartment throughsaid air flue in thermal exchange relationship with said second 6stopping the operation of said compressor.

References Cited in the file of this patent UNITED STATES PATENTS 102,065,604 Miller Dec. 29, 19 36 2,095,010 Phillip Oct. 5, 1937 2,117,104Rorison May 10, 1938 2,133,956 Buchanan Oct. 25, 1938 2,418,150Adriansen et al. Apr. 1, 1947 15 2,589,551 Iwashita Mar. 18, 19522,594,036 Knapp Apr. 22, 1952 2,692,482 Shoemaker Oct. 26, 19542,723,533 Mann Nov. 15, 1955 2,807,149 Williams Sept. 24, 1957 5 6 1evaporator, means responsive to the temperature of the air at the outletof said air flue for starting and stopping said fan means, and meansresponsive to the temperature of a portion of said second evaporator forstarting and

